
Fiona Moriarty
IRONMAN® World Championships
Fiona's headline numbers
Fiona's strategy
Fueling
T - 1-4hrs: Ate a carb rich meal (Low in fat & fibre)
T - 15mins: Took in a final dose of carb
"I stayed on top of my timing for fueling and had pretty consistent energy levels, other than the third lap of the run when I was forced to use the on course support."
After a tough day in Kona at the IRONMAN® World Champs last year with terrible stomach issues, a 7 out of 10 rating for GI comfort this year was a win for Fiona. Fueling on the bike went smoothly, as she consumed mostly PF 300 Flow Gel for her carb intake, plus a few packs of PF 30 Chews. This enabled her to hit ~93g/h before starting the run, where she started with another round of Flow Gel. Unfortunately, she wasn’t able to get her second bottle of carbs at the personal needs station and had to switch to the on-course nutrition to try to get *some* carbs in. With her sensitive stomach, Fiona struggled with the deviation from what her body is used to and had to make several bathroom stops during the marathon. The drop to ~59g/h of carb took a toll on her energy levels, too. Still, she did well to stick it out and make do with what she could, finishing strong at the end.
Hydration
Taking on board an appropriate amount of fluid and sodium is essential to maintaining blood volume and supporting the cardiovascular effort needed to perform on race day.
Whilst the absolute amount of sodium and fluid consumed per hour is important, it’s critical to consider these in relation to each other. This is known as 'relative sodium concentration' and it’s expressed in milligrams per litre (mg/L). How much sodium you’re taking in per litre of fluid is more important than the absolute amount taken in per hour.
Fiona1146mg/L
Fiona has been Sweat Tested to dial in her hydration plan
Sweat sodium concentration (mg/L) is largely genetically determined and remains relatively stable. Knowing how salty your sweat is enables you to replace a good proportion of your sweat losses, which can range from 200-2,000mg/L.
Given Fiona's losses are High (1,146mg/L), nailing her hydration strategy becomes especially crucial when it's hot and/or humid.
Learn moreT - 60mins: Drank ~500ml of strong electrolyte drink
"I felt like I really kept on top of my hydration this time and didn’t have any mistakes with it."
Knowing that sodium plays a role in nutrient absorption and that dehydration can affect the ability to stay on top of fueling, Fiona has worked hard to nail her sweat fluid and sodium needs. The on-course PH 1000 provided most of her sodium intake, filling up her bike hydration unit with this, plus an additional litre of PH 1500 to match her just above average losses. On the run, she continued with PH 1000 in her soft flasks to make sure she stayed consistent throughout the race. Although she had a bit of cramping on the bike, she attributes this to having to get off mid-hill after her chain dropped. Otherwise, her hydration plan and execution was spot on and kept her as hydrated as possible.
Caffeine
Beyond the Three Levers of Performance (carb, sodium and fluid), caffeine is one of only a few substances that is proven to improve performance for most endurance athletes as it can help stave off mental and physical fatigue.
T - 0-4hrs: Had a final hit of caffeine
Fiona typically doesn’t use caffeine during a race, as it doesn’t always sit well with her system. She did include one PF 30 Caffeine Gel this time out for a small energy boost, plus the minimal caffeine found in the cups of cola she picked up on the run. Given she had a coffee on race morning, she would have still had a bit of the stimulant in her system for the early part of the race, too, giving her *some* of the fatigue-masking effects. Going forward, she could test out incrementally larger doses of caffeine in training to see if her tolerance is improving, and possibly be able to reap the full ergogenic benefits of it in races down the line.
How Fiona hit her numbers
Here's everything that Fiona ate and drank on the day...
Final thoughts
“I was laser focused on getting my nutrition right for this race. After a super tough day at Kona last year because of a fueling error, I didn’t want that to be the reason I had another challenging race. Fortunately, my fueling was solid all the way around and I did my best, so I’m proud of the day!”

“It’s hard to plan for logistical issues like the ones Fiona encountered on the day, but she demonstrated excellent perseverance to stick to what she could in those circumstances. Her bike fueling was spot on, and nailing her relative sodium concentration throughout a full-distance race is a significant win. It was awesome to cheer for her in person and we can’t wait to see her accomplishments going forward!”
Fiona's full stats
Data Confidence
We rate each of our case studies from 1-5 based on the level of accuracy, and our confidence in the data.
There is an adequate level of accuracy in the data collected and the numbers reported. The athlete manages to recall what they ate and drank including most specifics (brands flavours quantities plausible estimations of volumes). However there are estimations made within the data which affect the overall confidence level in the data reported.